package com.zc.io;

import java.util.Random;

public class SuijishuTest {

	public static String getRandomString(int length){
		String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		Random random = new Random();
		StringBuffer sb = new StringBuffer();
		
		for(int i = 0 ; i < length; ++i){
			int number = random.nextInt(62);//[0,62)
			
			sb.append(str.charAt(number));
		}
		return sb.toString();
	}
	
	public static String getRandomString2(int length){
		Random random = new Random();
		
		StringBuffer sb = new StringBuffer();
		
		for(int i = 0; i < length; ++i){
			int number = random.nextInt(3);
			long result = 0;
			
			switch(number){
			case 0:
				result = Math.round(Math.random() * 25 + 65);
				sb.append(String.valueOf((char)result));
				break;
			case 1:
				result = Math.round(Math.random() * 25 + 97);
				sb.append(String.valueOf((char)result));
				break;
			case 2:
				sb.append(String.valueOf(new Random().nextInt(10)));
				break;
			}
		}
		return sb.toString();	
	}

	public static void main(String[] args){
//		System.out.println(getRandomString(10));
		System.out.println(getRandomString2(10));
	}
}
